Hotel reward programs are usually by family of hotel brands, while some hotels may have their own program. Given a certain hotel booking, you must be member of a program which the hotel is part.
For example, if you were to go to a Holiday Inn, then the program would be IHG (Intercontinental Hotel Group) which includes about a dozen other chains. If you do know which one you must look it up or call the hotel and ask which program they are part of.
Keep in mind that there are some agreements between airlines and hotels which certain hotels can accept the mileage program of some airlines and so if you are working towards status already with a Frequent Flyer program, you may choose that avenue.